Investigation on capacity loss mechanisms of lithium-ion pouch cells under mechanical indentation conditions

JOURNAL OF POWER SOURCES

卷:465

Article

Zhu, Xiaoqing^1,2,3  Wang, Hsin¹  Allu, Srikanth¹  Gao, Yanfei³  Cakmak, Ercan¹  Hopkins, Emma J.¹  Veith, Gabriel M.¹  Wang, Zhenpo² 

[1] Oak Ridge Natl Lab, POB 2009, Oak Ridge, TN 37831 USA

[2] Beijing Inst Technol, Natl Engn Lab Elect Vehicles, Beijing 100081, Peoples R China

[3] Univ Tennessee, Dept Mat Sci & Engn, Knoxville, TN 37996 USA

关键词: Lithium-ion cells;    Capacity loss;    Mechanical indentation;    Safety;    Internal short circuit;   

DOI  :  10.1016/j.jpowsour.2020.228314

来源: Elsevier

【 摘 要 】

Capacity loss was observed in Li-ion cells after mechanical deformation approaching the onset of internal short circuit (ISCr). In this paper, a series of indentation tests were carried out on commercial Li-ion cells of three capacities (500, 1500 and 2000 mAh). Both in-situ and ex-situ methods were used to investigate the mechanisms of indentation-induced capacity loss. After indentation test, the cell capacity reduced by 0.5%-6% of its original value. The incremental capacity (IC) analysis results showed that IC curves generally shifted to lower voltage region, indicating the increase in cell internal resistance. In addition, the fitting results of electrochemical impedance spectroscopy (EIS) indicated that mechanical indentation can result in a reduction in ohmic resistance and the increase in polarization resistance. Scanning electron microscopy (SEM) and X-ray computed tomography (XCT) results showed crushing of graphite, mud cracking of copper current collectors and enlarged pores in separator, which is proposed to be the main reasons for the increase in polarization resistance and permanent capacity loss. The rapid capacity loss due to mechanical abuse was compared with the long-term capacity fading.

【 授权许可】

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